The main goals of this research project are: (1) To evaluate the functional and morphological characteristics of human and animal arterial and/or venous endothelial and smooth muscle cells in vitro and in vivo and to compare their response to atherogenic stimuli. (2) To study by cytochemical and ultrastructural techniques the different stages of arterial repair under a variety of environmental conditions following reproducible and rapidly resolving vascular injury induced by techniques developed in our laboratory. (3) To determine the response of vascular cells in vitro to vasoactive stimuli and pharmacological agents under standardized laboratory conditions. (4) To investigate the role of platelet factors and lipoprotein fractions on arterial cell function during progression or regression of experimentally induced atherosclerosis.